Pros:

-Custom puzzles and mazes
-Custom made Portal signs, and an overall Portal feel (The whole point)

Cons:

-That bridge over goo... clipping a ton, and special spawned at the bottom and took our friends down via smoker and such.
-Puzzles before the finale were a bit much, possibly making the finale it's own dealie woulda been cooler in my mind. Puzzles were fun, but having to re-do them if you died on the finale.

Conclusion:

Worth a download if you like puzzles, thought, and/or Portal. Good fun

Pros:

-Nice looking
-I like the whole, frozen then... not, thing.
-Good flow
-Loved the music... 

Cons:

-Various small bugs, mainly with elevators, and their ability to kill all or a few survivors, leaving you to play a level with half yur crew. Also one time, the elevator on the way back up, just kinda left us at the bottom, had to attack each other to re-try. (To be fair, I enjoyed gunning down my friends)

Conclusion:

Definately worth a download, just watch that elevator, it's evil.

(And death chargers)

Pros:

-Nice design
-Clean flow
-Overall enjoyable

Cons:

-Little short; summoned the rescue vehicle without realizing that I was infact already at the finale.
-Lack of weapons

Conclusion:

Definately worth getting.